AS per MSDN, ASCII only extends up to 127. 128..255 is commonly used for ANSI characters. Above that is only Unicode. If you have any questions please go through below link that might be helpful to you.https://social.msdn.microsoft.com/Forums/en-US/30c27587-82a8-4fb0-a94b-3739f9c8e53d/detecting-unicode-character?forum=csharplanguage--------------------------------------------------------------------------------Give respect to your work, Instead of trying to impress your boss.

Other wise, You will check the below mentioned Links. It will provide some ideas for,1.http://stackoverflow.com/questions/4459571/how-to-recognize-if-a-string-contains-unicode-chars2.http://stackoverflow.com/questions/1522884/c-sharp-ensure-string-contains-only-ascii3.http://stackoverflow.com/questions/123336/how-can-you-strip-non-ascii-characters-from-a-string-in-c4.http://www.codeproject.com/Questions/1107914/How-to-find-out-that-string-contain-unicode-charac